May be a dumb question from a newbie...

My apologies if the answer to this is obvious, but I am new to Fongo and don't want to risk an unpleasant surprise on my next cell bill.
I am traveling to Buffalo from Toronto. Am I correct in my understanding that if I find a free Wi-Fi spot in Buffalo, that I can call home free with Fongo?
My wife is new to Fongo as well. Is it better to call her Fongo number versus her regular number or does that not matter?
Thanks in advance for your help.
I am traveling to Buffalo from Toronto. Am I correct in my understanding that if I find a free Wi-Fi spot in Buffalo, that I can call home free with Fongo?
My wife is new to Fongo as well. Is it better to call her Fongo number versus her regular number or does that not matter?
Thanks in advance for your help.